My audio system is option S752 "Individual Audio System" So it had a BM53, with widescreen etc, plus DSP including the big subwoofers. Now with the BM54 in place, the sound is quite acceptable to me. I know car audio systems can be a lot better, but for me and wary of the law of diminishing returns, plus wanting to keep it basically in original spec, means that it sounds just fine to me. I have a cheapo Bluetooth hooked into the Aux input so I'm good to go. Plus when I'm sick of the music there always the popped sunroof and 3rd gear option for a bit of "metallica"..